In the past narrow fabric needle looms have employed either a small wire around which the weft thread is wound during weaving by the needle as it enters the shed and which runs continuously along one side of the narrow woven fabric. The use of such a wire woven into the narrow fabric does provide to a certain extent a satisfactorily straight selvage. Other known looms employed a pointed plate secured to the mounting block of the loom which defines the gap through which woven material passes as it leaves the shed. In such arrangements, the pointed plate has a downwardly extending point formed thereon projecting outwardly from the mounting block a distance of a few millimeters with the point on the plate also serving to hold the weft thread in a desired position where a selvage is to be formed on the woven material as the needle enters the shed. Both of these known arrangements have not proven entirely satisfactory due in part to the requirement of the need for additional material in the form of a wire, which must not be either too small or too large and in the case of the pointed plate, its displacement outwardly from the mounting block is too great to assure formation of a straight selvage along the length of the woven narrow fabric.
Further, prior know automatic narrow-fabric needle looms feed the weft thread continuously as the needle holding the weft thread is reciprocated in and out of the shed during the weaving process. However, consumption of the weft thread during weaving is not continuous. As the needle swings into the shed, temporarily there is a great demand for thread. When the needle swings back and while out of the shed, the demand for weft thread is very low or substantially none. Therefore, between the weft thread feed and the needle a mechanism must be provided by which the weft thread is held with suitable tension during such irregular consumption of the weft thread.
In prior known devices, weft thread feed is effected by two rubber-coated cylindrical rollers which are in contact with each other and accommodate the weft thread between them. One cylindrical roller is motor driven while the second roller is spring biased into engagement with the first roller so that it is caused to follow the first roller. Both cylindrical rollers have the same diameter so that rotating speed of the driven cylindrical roller must be changed in order to adjust the weft thread feed to the demand. For this purpose, the driven cylindrical roller requires a motor use rotating speed can be infinitely variable and is therefore somewhat expensive.
In addition to the above, known prior art weaving looms employ serially arranged reciprocating header frame assemblies to form the shed during weaving. The known header assembly designs are difficult to change in order to accommodate programming of the loom to weave a different pattern and further employ header elements which sometimes can be swivelled in their mount due to warp tension. When thus swivelled, the header elements tend to remain in the swivelled condition causing abnormal wear on the warp threads and possible breakage. Additionally, the machinery for reciprocating the serially arranged header assemblies up and down in known looms requires somewhat heavy linkages and couplings which are complex in design and difficult to maintain because of wear.
Another problem encountered with known narrow fabric needle looms concerns the difficulty in altering the weaving process to provide a different number of picks of the weft for a given length of woven material. With known looms, considerable breakdown of the linkages driving the needle, reed and take-up roll, all of which movements must be properly synchronized, require considerable time and work on the part of a technician to accommodate such changes in the number of picks provided for length of woven material.
During weaving at the point in the movement of the needle where it is entirely within the shed, a weaving needle picks off a length of the weft thread to perform what is known as a pick. For this purpose, latching needles have been used in the past as described in German Pat. No. 2940704 published Apr. 17, 1980, for example. The present invention provides an improved reciprocating latching needle drive which is coordinated with the movement of the needle in a simple and expeditious manner.
In prior known needle loom weaving systems, the warp spool for supplying warp thread to the loom has been braked through the use of weights which are depended from the peripheral edges of the spool or the spool supports with the weights used being gauged to provide a desired amount of warp thread tension. This arrangement, while it works, has some disadvantages in that it causes a jerking rotational motion of the warp spool which is not altogether satisfactory.